Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/03—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite
  • C04B35/057—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite based on calcium oxide
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B59/00—Obtaining rare earth metals
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
  • C22B9/006—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals with use of an inert protective material including the use of an inert gas
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
  • C22B9/16—Remelting metals

Definitions

• This invention relates to a method for the production of a lanthanide-containing alloy and more particularly to a method for the production of a highly clean lanthanide-containing alloy useful as a target alloy for a magneto-optical (M-O) disc.
• M-O magneto-optical
• LaNi 5 , SmCo 5 , and misch metal (Mm)-Ni type alloys such as, for example, MmNi 4 .5 Al 0 .5, MmNi 4 .5 Mn 0 .5, and MmNi 4 .7 Al 0 .3 Zr 0 .1 are capable of easily occluding large volumes of hydrogen and, therefore, are utilized as hydrogen-absorbing alloys.
• SmCO 5 (Sm 36%), Sm 2 Co 17 , Ce-Co (Ce 20%), (Sm 1-x Pr x ) Co 5 , Nd-Fe (Nd 20 to 25%), Sm 2 (FeCuZrCo) 17 (Sm 25% and Co 50%), and Nd 8 ⁇ 30 B 2 ⁇ 28 Fe balance of 100 (such as, for example, Nd 15 B 8 Fe 77 ) exhibit extremely strong magnetic properties owing to the magnetic characteristics inherent in lanthanides and, therefore, are extensively utilized as permanent magnets in small motors.
• An amorphous alloy of the composition of (Fe 0 .82 B 0 .18) 0 .9 - Tb 0 .05 La 0 .05 has also been developed as a magnet.
• Fe-based, Co-based, and Ni-based amorphous alloys containing Gd, Tb, and Dy such as GdCo, GdFe, DyFe, GdTeFe, TbFeCo, TbDyFe, GdTbFe, and GdTeCo form magnetic films excellent in the square-shape property in hysteresis loop, exhibit outstanding magnetizing property and erasing property, permit high-density recording, and undergo deterioration through aging only minimally, the efforts currently continued on the research and development of these alloys are attracting much interest and arousing great expectations.
• Yb-Al, Yb-Zr-Al and Mm-Zr-Al have found utility as large-capacity Al cables of improved thermal stability, TiGd (Gd 5%) as a strong light alloy, MgNd as a creep-resistant Mg alloy, and NiCrLa and FeCrLa as heat-resistant alloys capable of resisting oxidation at elevated temperatures.
• amorphous magnetic films of the combinations of rare earth metals (RE) such as Gd, Tb and Dy with transition metals (TM) such as Fe, Co and Ni which are enumerated below have been developed as M-O disc memory media.
• Gd-Tb-Fe Gd-Tb-Fe, Gd-Tb-Co, Tb-Fe-Co, Tb-Dy-Fe, Gd-Tb-Fe-Ge, Gd-Co, Tb-Fe, Gd-Fe, Fe-Co-Tb-Gd, Tb-Dy-Fe-Co, Dy-Fe, and Gd-Fe-Bi.
• the Co-Ge, Gd-Fe and Tb-Fe type alloys were the first to attract attention as promising M-O recording materials. Since then, the attention is switching to the Tb-Fe-Co and Gd-Tb-Co type alloys owing to their merits in compositional sensitivity and recording density.
• the alloys have high sensitivity to recording and erasing because they have relatively low Curie points and are also capable of compensation recording. They permit recording and erasure by means of a semiconductor laser (LD).
• LD semiconductor laser
• the alloys have low medium noise because they have amorphous textures. Their Kerr rotation angles are relative large, ranging from 0.2° to 0.35°. Thus, the SN ratios of their regenerated signals are large.
• the alloys form perpendicularly magnetizing films, they permit high-density recording and also permit efficient use of the pole-Kerr effect and the Faraday effect of high M-O performance.
• the alloys are capable of forming films of large surface areas on substrates of varying types.
• the alloys permit their mixing ratios of component metals to be varied continuously and can be admixed freely with various elements relatively.
• These lanthanide-containing alloys have been heretofore produced by being melted and cast in alumina-based crucibles, for example.
• lanthanides are highly reactive and readily react with oxygen (O), sulfur (S), and nitrogen (N).
• O oxygen
• S sulfur
• N nitrogen
• the high activity inherent in lanthanides induces problems such as contamination of alloys with refractory material exposed to the melts and formation of lanthanide oxides, decrease of lathanide contents in produced alloys, and breakage of refractory material in an extreme case.
• the melt is contaminated with an alumina-based refractory material through the reaction of the following formula, in which Ln stands for a lanthanide element.
• the produced alloy does not acquire sufficiently high purity.
• photomagnetic discs are required to exhibit a high performance in terms of sensitivity of recording regeneration, and erasure, recording density, anisotropy of perpendicular magnetization, Kerr rotation angle, and service life. These properties are profoundly affected by the purity and homogeneity of the target alloy for M-O disc.
• the lanthanide-containing alloys cannot be produced with high purity and in high homogeneity as described above.
• RE component such RE component as Tb, Gd or Dy
• the melts are highly susceptible of contamination due to inclusion of oxygen and the alloys consequently produced are highly susceptible of fructure, the method adopted for their production has many problems to be solved.
• An object of this invention is to provide a method for the production of a lanthanide-containing alloy, which permits easy production of a lanthanide-containing alloy of high purity, having low oxygen and sulfur contents and enjoying freedom from contamination with the refractory material.
• Another object of this invention is to provide a method for the production of a lanthanide-containing alloy, which permits production of a lanthanide-containing alloy of extremely fine quality, excelling in magnetic properties, corrosionproofness, and thermal stability and exhibiting high mechanical strength.
• Yet another object of this invention is to provide a method for highly stable and efficient production of a lanthanide-containing alloy.
• a further object of this invention is to provide a method for the production of a lanthanide-containing alloy, permitting the lanthanide-containing alloy to be re-melted and re-cast easily and ensuring efficient reclamation of the alloy from scraps thereof.
• this invention concerns a method for the production of a lanthanide-containing alloy, which method is characterized by retaining the melt of said alloy by the use of a container having the inner surface thereof formed of a calcia-type refractory possessing a CaO content of not less than 90% by weight in a non-oxidizing atmosphere.
• lanthanide-containing alloy means an alloy containing at least one lanthanide element selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Td, Dy, Ho, Er, Tm, Yb, and Lu.
• the lanthanide-containing alloy include alloys of 3 to 80%, particularly not less than 10%, and preferably 10 to 50%, of such lanthanides with at least one member selected from the group consisting of Al, Cr, Fe, Mn, Ni, Cu, V, Li, Co, Ti, Ta, W, Sn, Zr, Mo, Mg, Ga, Nb, Si, and Bi.
• the method of this invention is effective in producing target alloys containing not less than 10%, preferably 10 to 50%, of lanthanide elements for use in photomagnetic discs. Concrete examples of the alloys answering the description given above are shown below.
• such a lanthanide-containing alloy as shown above is produced by heating the alloy by the conventional method such as, for example, a high-frequency or low-frequency induction heating by the use of a container having the inner surface thereof formed of a calcia-based refractory possessing a CaO content of not less than 90% in a non-oxidizing atmosphere.
• the materials of the CaO-based refractory of which the inner surface of the container used for the production of the lanthanide-containing alloy in the present invention are of calcia (CaO), dolomite obtained by enriching CaO, and ZrO 2 and Y 2 O 3 as coexisting oxides.
• Lanthanide type oxides are also available. Because of high density of texture, electrically fused clacia proves particularly desirable among other CaO products of varying grades.
• Calcia (CaO) products obtained by firing quick lime, limestone, and slaked lime are also desirable.
• the container which is formed of a CaO-based refractory possessing a CaO content of not less than 90%, particularly not less than 95%, and preferably not less than 98%.
• the contents of CaF 2 and CaCl 2 are desired to be as low as permissible.
• the content of CaF 2 is desired to be not more than 1% and that of CaCl 2 to be not more than 0.5%.
• the atmosphere in which the production is effected is desired to be an atmosphere of such inert gas as argon or helium.
• the pressure of the atmosphere is desired to be not less than 10 torrs, preferably to keep in the range of 25 to 100 torrs.
• the temperature for the production is desired to be 50° to 200° C., preferably 100° to 150° C., higher than the melting point of the alloy under treatment. If the retention time is too long, there ensues the possibility of the melt being contaminated. To avoid this contamination, therefore, the retention time is desired to keep approximately in the range of 5 to 10 minutes, preferably 5 to 6 minutes.
• the melt of the lanthanide-containing alloy obtained by the method of this invention is then poured into a die of a desired shape and converted into an ingot.
• the hot ingot is desired to be gradually cooled in a preheated iron die at a rate of not more than 1° C./minute, preferably 0.5° to 1° C./minute.
• the produced metal has a notably lowered content of entrained oxygen and it can be re-melted by suitably controlling and adjusting the conditions of production.
• CaO has extremely high stability to resist the melt of an alloy containing a highly active metal and it is stable even in the melt of a lanthanide-containing alloy. Unlike Al 2 O 3 which reacts with a lanthanide and forms a corresponding lanthanide oxide, CaO only springly forms an oxide with a lanthanide. CaO, therefore, is incapable of decreasing the lanthanide content of the melt of the lanthanide-containing alloy or contaminating the melt with impurities. Particularly, in accordance with the method of this invention, the oxygen content in the lanthanide containing alloy is notably lowered.
• the alloy produced or the alloy remelted by the method of the present invention possesses an oxygen content lowered to the range of 150 to 500 ppm.
• the sulfur in the melt of the lanthanide-containing alloy first undergoes the following conversion:
• the sulfide is eventually absorbed by the crucible wall. Consequently, the oxide and sulfide contents are notably decreased, rendering it possible to produce a lanthanide-containing alloy of high purity.
• the lanthanide-containing alloy of low oxygen and sulfur contants, free from contamination with the refractory can be easily obtained.
• Particularly the oxygen content of the alloy is notably low.
• the produced alloy therefore, exhibits highly satisfactory performance in terms of magnetic properties, corrosionproofness, and thermal stability.
• the alloy also enjoys highly improved mechanical strength.
• the method enables the lanthanide-containing alloy to be re-melted and re-cast easily and, therefore, ensures efficient reclamation of the alloy from scraps thereof.
• the method of this invention thus, permits a lanthanide-containing alloy of high purity to be produced easily and proves highly advantageous from the economic point of view.
• the method of this invention is effective in producing a target disc containing not less than 10% of Gd, Tb or Dy for use in a M-O disc.
• the alloy obtained by this invention eliminates the problem of cracking and permits provision of M-O discs of high performance.
• the present invention can be adopted satisfactorily for the melting of lanthanide-containing alloy scraps.
• a varying lanthanide-containing alloy indicated in Table 1 was placed in a CaO-based crucible or Al 2 O 3 -based crucible of a varying composition shown in Table 2, then set in an internally heating type induction furnace having an output of 10 kw and a frequency of 50 KHz, melted in an atmosphere of 2 torrs of argon, kept at a temperature 200° C. higher than the melting point of the relevant alloy for 10 minutes.
• the alloy consequently produced was assayed for O and S contents by chemical analysis and fluorescent X-ray. The results are shown in Table 1.
• a 30%Fe-30%Co-20%Gd-20%Tb alloy was produced by following the procedure of Example 1, excepting an atmosphere of 25 torrs of argon was used instead and the temperature of melting was changed to 50° C. higher than the melting point of a relevant alloy.
• a 40%Gd-60%Fe alloy (melting point 1,220° C.) was re-melted in a CaO-based crucible of the composition shown in Table 2, with the crucible placed in an internally heating type induction furnace having an output of 10 kw and a frequency of 50 kHz, heated in an atmosphere of 250 torrs of argon at a varying temperature shown in Table 5, and retained at the temperature for a varying length of time indicated in Table 5.
• the alloy consequently obtained was assayed for O and S contents by chemical analysis and fluorescent X-ray analysis.
• a 40%Tb-30%Fe-30%Co alloy was produced in a CaO-based crucible of a varying composition indicated in Table 2, with the crucible set in an internally heating type induction furnace having an output of 10 kw and a frequency of 50 kHz, heated in an atmosphere of 25 torrs of argon at a temperature 100° C. higher than the melting point of the relevalent alloy, and retained at the temperature for a varying length of time from 5 to 10 minutes.
• the melt consequently obtained was poured in a preheated die and gradually cooled at a varying rate shown in Table 6 to afford an ingot.
• the ingot thus obtained was assayed for O and S contents by chemical analysis and flurescent X-ray analysis.
• a varying lanthanide-containing alloy indicated in Table 7 was placed in a CaO crucible or Al 2 O 3 crucible of a varying composition indicated in Table 2 and treated by following the procedure of Example 1.
• the alloy consequently obtained was assayed for O and S contents by chemical analysis and fluorescent X-ray analysis. The results are shown in Table 7.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Metallurgy (AREA)
• Ceramic Engineering (AREA)
• Geology (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Structural Engineering (AREA)
• Manufacture And Refinement Of Metals (AREA)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26465963

Family Applications (1)

Country Status (4)

Cited By (2)

Families Citing this family (2)

Citations (1)

• 1986
  • 1986-11-05 US US06/927,790 patent/US4695427A/en not_active Expired - Fee Related
  • 1986-11-13 GB GB8627119A patent/GB2183252B/en not_active Expired
  • 1986-11-18 DE DE19863639332 patent/DE3639332A1/de active Granted
  • 1986-11-19 NL NL8602943A patent/NL8602943A/nl not_active Application Discontinuation

Patent Citations (1)

Also Published As

Similar Documents

Legal Events